1. Field of the Invention
The present invention relates to a filtering apparatus for an electronic musical instrument which varies tone volume and tone color of a musical tone in a manner similar to that of an acoustic musical instrument.
2. Prior Art
Conventionally, an electronic musical instrument provides an envelope generator (hereinafter referred to as "EG") which generates an envelope signal controlling the tone volume and the tone color of the musical tone signal, and memory storing data for controlling tone parameters concerning the tone volume and tone color by use of the EG. An example of such electronic musical instrument has been disclosed in U.S. Pat. No. 4,301,704, which application was filed by the same applicant of the present invention.
When the player depresses a key of a keyboard and the like, the electronic musical instrument reads out the data for controlling the tone parameter from the memory in response to a keycode corresponding to the depressed key, and then changes the tone volume and the tone color of the musical tone signal on the basis of the read-out data.
However, since the data for controlling the tone parameter is stored in the memory in advance, the variations of the tone volume and the tone color must be limited.
In addition, the parameters are respectively set by each tone color and tone pitch. Therefore, the conventional electronic musical instrument needs a large memory to store the data for controlling the parameters.